Light-emitting diode device and display device

ABSTRACT

A light-emitting diode (LED) device includes: an LED chip, a first lens, and a second lens. The first lens is disposed over the LED chip and configured to increase the light extraction efficiency of the LED device, and the first lens includes a first content of titanium dioxide. The second lens is disposed over the first lens and configured to alter the light pattern of the LED device, and the second lens includes a second content of titanium dioxide. The second content of titanium dioxide is more than the first content of titanium dioxide.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Taiwan Application Serial Number108147251, filed Dec. 23, 2019, which is herein incorporated byreference in its entirety.

BACKGROUND Field of Invention

The present disclosure relates to a package structure of alight-emitting diode device.

Description of Related Art

A light-emitting diode (LED) is a solid-state semiconductor devicecapable of converting electrical energy into light energy. Packaging theLED refers to encapsulating the LED chip in a particular structure whichprotects the LED chip and light can travel through.

FIG. 1A illustrates a conventional package structure of an LED device10. The package structure of the LED device 10 is a flip-chip type ofchip-scale package (CSP). An LED chip 20 is disposed on a printedcircuit board (PCB) 40 and is electrically connected to the circuits ofthe PCB 40 through anodized pad 22 and a negative pad 24. The outer partof the LED chip 20 is covered with an encapsulant 30 to protect the LEDchip 20. The material of the encapsulant 30 is often a silicone resinhaving a light refractive index of about 1.4 to 1.51.

In the conventional LED device 10, non-epoxy-resin is often used as theencapsulant 30. However, if the encapsulant 30 is exposed to ultraviolet(UV) lights emitted from the UV LED chip 20 for a long time, suchencapsulant 30 will gradually yellow and affect the light extractionefficiency of the LED device 10.

In addition, FIGS. 1B and 1C respectively show the sample of traced raysand the Candela plot for light distribution of the LED device 10 shownin FIG. 1A. A high proportion of the light beams generated by the LEDchip 20 are emitted from the upper side of the LED device 10, and thelight distribution pattern shown in the Candela plot is an ellipticalshape. Therefore, the intensity distribution of the light field providedby the conventional LED device 10 is overly concentrated in the center,which results in poor performance of light uniformity and light emissionangles. Because an LED device is a point light source, a conventionalLED device often requires an additional design to diffuse the lightbeams emitted by the LED device more evenly. For example, a secondaryoptical lens can be added to the LED device in order to provide thedesired light pattern.

For instance, LED devices are utilized in display devices. Theapplications of the display devices are gradually increasing, forexample, a display device now can be integrated with multiple functions,such as various camera, communication, display, or other features. Theresolutions of display devices are also gradually upgrading; forexample, 4K resolution display devices are upgrading to 8K resolutiondisplay devices. Utilizing mini LED backlight modules in the displaydevices can not only provide more and smaller local dimming zones forthe display devices, but also achieve high-contrast performance requiredfor high dynamic range (HDR) imaging. In the direct type backlightmodules of the existing display devices, which can be LCD TV or computerdisplays, a secondary optical lens is often disposed to cover the LEDdevice in order to redistribute the light emitted by the LED device, sothe light field can meet the requirements of the display devicescontaining optical cavities with heights more than 10 mm.

However, for the ultra-thin display devices, which contain opticalcavities with heights equal to or smaller than 10 mm, the direct typebacklight modules cannot be the conventional design mentioned above.Since the minimum height of the optical cavity is restricted by theconventional secondary optical lens for the LED devices, the ultra-thindisplay device having relatively tiny space inside cannot provide thesecondary optical lenses enough light refraction distances and anglesrequired for altering the light pattern of the LED devices, which willcause defects such as uneven mixing of light in the backlight modules.

SUMMARY

Some embodiments of the present disclosure provide an LED deviceincluding an LED chip, a first lens, and a second lens. The first lensis disposed over the LED chip and configured to increase the lightextraction efficiency, and the first lens comprises a first content oftitanium dioxide. A second lens is disposed over the first lens andconfigured to change the light pattern, and the second lens comprises asecond content of titanium dioxide. In the LED device, the secondcontent of titanium dioxide is more than the first content of titaniumdioxide.

In some embodiments, the material of the first lens and the second lensincludes a silicone epoxy resin.

In some embodiments, the first content of titanium dioxide in the firstlens is more than 0.01 weight percent of the first lens.

In some embodiments, the first content of titanium dioxide in the firstlens is less than 0.5 weight percent of the first lens.

In some embodiments, the second content of titanium dioxide in thesecond lens is more than 0.5 weight percent of the second lens.

In some embodiments, the second content of titanium dioxide in thesecond lens is less than 2 weight percent of the second lens.

In some embodiments, the average particle diameter of the titaniumdioxide of the first lens and the titanium dioxide of the second lens issmaller than 1/10 of the wavelength of the emitted light of the LEDchip.

In some embodiments, the average particle diameter of the titaniumdioxide of the first lens and the titanium dioxide of the second lens issmaller than 40 nm.

In some embodiments, the LED chip is a blue light chip.

In some embodiments, the LED device is a chip-scale package structure.

Some embodiments of the present disclosure provide an LED deviceincluding an LED chip, a first lens, and a second lens. The first lensis disposed over the LED chip and includes titanium dioxide less than0.5 weight percent of the first lens. The second lens is disposed overthe first lens and includes titanium dioxide more than 0.5 weightpercent of the second lens.

In some embodiments, the titanium dioxide of the first lens is dispersedin the first lens.

In some embodiments, the titanium dioxide of the second lens isdispersed in the second lens.

In some embodiments, the second lens includes a resin material, and thetitanium dioxide of the second lens is formed as a thin film overlayingthe resin material of the second lens.

In some embodiments, the first lens directly contacts the LED chip.

In some embodiments, the second lens directly contacts the first lens.

In some embodiments, the first lens is configured to increase the lightrefraction.

In some embodiments, the light refractive index of the second lens issmaller than the light refractive index of the first lens.

In some embodiments, the light transmittance of the second lens is lessthan the light transmittance of the first lens.

Some embodiments of the present disclosure provide a display deviceincluding any of the LED devices of the embodiments of the presentdisclosure, and the display device has an optical cavity having a heightsmaller than 10 mm.

In some embodiments, the LED device is a direct-light-type backlightmodule of a display device.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1A illustrates a cross-sectional view of a conventional LED devicehaving a chip-scale package.

FIG. 1B illustrates the ray trace plot of a conventional LED devicehaving a chip-scale package.

FIG. 1C illustrates a Candela plot (i.e., a light distribution curve) ofa conventional LED device having a chip-scale package.

FIG. 2 shows the relationship between the various content of titaniumdioxide and light transmittance.

FIG. 3 shows the relationship between the various content of titaniumdioxide and light refractive index.

FIG. 4A illustrates a cross-sectional view of the structure of an LEDdevice in accordance with some embodiments of the present disclosure.

FIG. 4B illustrates a ray trace plot of an LED device in accordance withsome embodiments of the present disclosure.

FIG. 4C illustrates a Candela plot (i.e., a light distribution curve) ofan LED device in accordance with some embodiments of the presentdisclosure.

FIGS. 5A and 5B illustrate cross-sectional views of an LED device inaccordance with some embodiments of the present disclosure.

FIGS. 6A and 6B are cross-sectional views of an LED package structure inaccordance with some embodiments of the present disclosure.

FIG. 7 illustrates an exploded view of a backlight module in accordancewith some embodiments of the present disclosure.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations), and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

In view of the problems of conventional LED devices, such as undesiredlight pattern or uneven mixing of light, some embodiments of the presentdisclosure provide the solution, which can alter the light pattern andimprove the light extraction efficiency of an LED device by disposing atwo-layer lens, wherein the two layers have different content oftitanium dioxide respectively.

FIG. 2 shows the relationship between the various content of titaniumdioxide in a silicone epoxy resin layer and light transmittance of thesilicone epoxy resin layer. The particle diameters of the titaniumdioxide in the tests shown in FIG. 2 are smaller than 40 nm. As thetests shown in FIG. 2, the silicone epoxy resin layers with differentcontent of titanium dioxide (TiO₂), such as 0.01 weight percent, 0.1weight percent, 0.5 weight percent, and 1 weight percent, were testedrespectively for obtaining the light transmittance of the testedsilicone epoxy resin layers at different light wavelengths.

The dotted line in FIG. 2 is the wavelength of 450 nm, which is theapplied wavelength of a typical blue LED chip. FIG. 2 shows thatincreasing content of titanium dioxide particles leads to a significantreduction of light transmittance for the light with the wavelengths inthe range of UV, such as the light with wavelengths shorter than 400 nm.Accordingly, a silicone epoxy resin layer mixed with titanium dioxideparticles disposed on the LED chip can effectively filter a portion ofthe emitted UV light and improve the color purity of the blue lightemitted from the LED device. In addition, a silicone epoxy resin layerhas better resistance to UV light, so the silicone epoxy resin layerwill not yellow as easily as the encapsulant 30 used in the conventionalLED devices. The mixed titanium dioxide particles also reduce thetransmittance of UV light and enhance absorption of UV light.

FIG. 2 also shows that when 1 weight percent titanium dioxide was addedinto the silicone epoxy resin, the light transmittance at the wavelengthof 450 nm was about 20%. When 0.5 weight percent titanium dioxide wasadded into the silicone epoxy resin, the light transmittance at thewavelength of 450 nm was about 65%. When 0.01 to 0.1 weight percenttitanium dioxide was added into the silicone epoxy resin, the lighttransmittance at the wavelength of 450 nm was about 75% to 85%.Therefore, when less than 0.1 weight percent titanium dioxide is addedinto the silicone epoxy resin, the effect of altering the lighttransmittance made by the added titanium dioxide becomes smaller.According to the test results shown in FIG. 2, a silicone epoxy resinlayer mixed with titanium dioxide particles disposed on the LED chip canprovide the desired light transmittances or light patterns by adjustingthe content of the titanium dioxide within the silicone epoxy resinlayer.

FIG. 3 shows the relationship of titanium dioxide content in a siliconeepoxy resin layer and the refractive index for blue light withwavelengths from 445 to 450 nm in such silicone epoxy resin layer,wherein the diameters of the tested titanium dioxide particles aresmaller than 40 nm. According to FIG. 3, when the silicone epoxy resinlayer is not mixed with titanium dioxide particles, the refractive indexfor blue light in the silicone epoxy resin layer is about 1.5. When thecontent of titanium dioxide particles is gradually increased to 0.1weight percent, the refractive index for blue light in the siliconeepoxy resin layer increases as well. The highest refractive index forblue light, about 1.61 to 1.62, in the test is reached at 0.1 weightpercent titanium dioxide particles mixed within the silicone epoxy resinlayer. If the content of titanium dioxide particles is increased over0.1 weight percent, the refractive index for blue light in the siliconeepoxy resin layer decreases in contrast. For example, when the contentof the titanium dioxide particles is gradually increased to 0.5 weightpercent, the refractive index for blue light in the silicone epoxy resinlayer gradually decreases to about 1.58.

According to the test results shown in FIGS. 2 and 3, the titaniumdioxide powder having nanometer-scale particle size mixed in theencapsulant of silicone epoxy resin can provide various opticalproperties. When the content of titanium dioxide particles is low, e.g.,less than 0.1 weight percent, the effect on the transmittance of lighthaving wavelengths longer than 450 nm is small, i.e., there is not muchreduction in transmittance while the content of titanium dioxidegradually increases to 0.1 weight percent. At the same time, therefractive index of the silicone epoxy resin layer mixed with titaniumdioxide particles rises from 1.51 to about 1.61, while the content oftitanium dioxide particles gradually increases to 0.1 weight percent.Alternatively, if the content of mixed titanium dioxide particles ismore than 0.5 weight percent, the titanium dioxide particles willaggregate within the silicone epoxy resin and cannot maintain dispersionstatus, thereby the light extraction efficiency is no longer improved bythe refractions between particles within the silicone epoxy resin layer.The aggregation phenomenon of particles may result in Rayleighscattering and leads to a significant decrease in transmittance of bluelight.

Therefore, a two-layer structure of lenses disposed in an LED device isdisclosed according to some embodiments of the present disclosure, anddifferent content of titanium dioxide particles are added into thesilicone epoxy resin layers, wherein the first layer of the lenses isconfigured to increase the light extraction efficiency, and the secondlayer of the lenses is configured to alter the light pattern of theemitted light.

FIG. 4A illustrates an LED device 100 according to some embodiments ofthe present disclosure. The LED device 100 includes a substrate 110 andan LED structure 120 which is disposed on the substrate 110. The LEDstructure 120 includes a first pad 132, a second pad 134, an LED chip140, a first lens 150, and a second lens 160.

In some embodiments of the present disclosure, one or more LEDstructures 120 may be disposed on the substrate 110, and the substrate110 may be a printed circuit board (PCB), for example. In someembodiments, the substrate 110 is coated with white paint having 80% to90% light reflectivity, so the light emitted from the LED chip 140toward the substrate 110 will be reflected outward.

The LED chip 140 is disposed on the substrate 110 and is electricallyconnected to the circuits of the substrate 110 through the first pad132, such as an anode pad, and the second pad 134, such as a cathodepad. In addition, in some embodiments, the LED chip 140 is fixed on thesubstrate 110 by an adhesive, such as epoxy resin.

In some embodiments of the present disclosure, the LED chip 140 is ablue light LED chip, such as a gallium nitride (GaN) chip or a galliumphosphide (GaP) chip, and the emitted light of the LED chip 140 haswavelengths between 430 and 480 nm, for example, 440 to 460 nm.

The first lens 150 is disposed over the LED chip 140. In someembodiments, the first lens 150 directly contacts the LED chip 140. Thefirst lens 150 is made of silicone epoxy resin containing titaniumdioxide particles dispersed therein, wherein the titanium dioxideparticles are at a content in a range of about 0.01 to about 0.5 weightpercent. The particle diameter of the titanium dioxide particles issmaller than 1/10 of the wavelength of the light emitted from the blueLED chip 140, for example, smaller than 40 nm.

In some embodiments of the present disclosure, the titanium dioxideparticles are mixed with the silicone epoxy resin which forms the firstlens 150 on the LED chip 140 by a molding process.

In some embodiments of the present disclosure, the first lens 150 isconfigured to increase the light extraction efficiency of the LEDdevice. According to Snell's Law, when the light is toward an opticallyrarer medium from an optically denser medium at an angle of incidencewhich is greater than the critical angle, the light will not refractthrough the optically rarer medium but reflect back to the opticallydenser medium. Such phenomenon refers to total internal reflection. Forexample, a gallium nitride (GaN) LED chip is used as the light source,which is the optically denser medium with the refractive indexes n=2.5.If the difference in refractive index between the encapsulant and theGaN LED chip covered by the encapsulant is too large, a large portion ofthe emitted light will be reflected back in the inside of the GaN LEDchip in accordance with Snell's Law, and therefore the light extractionefficiency will be reduced. The refractive index of the encapsulatingsilicone resin contacting the LED chip in the prior art LED device iswithin the range from about 1.4 to about 1.51, so the light extractionefficiency of the conventional LED device is affected by the differencein the refractive indexes of materials.

Conversely, in the embodiments of the present disclosure, the first lens150 in the LED structure 120 is made of silicone epoxy resin, wherein aparticular proportion of titanium dioxide particles is added into thesilicone epoxy resin, and silicone epoxy resin having titanium dioxideparticles added forms the polygonal geometry shape of the first lens 150which contacts the LED chip 140 directly. The first lens 150 can beformed by a molding process and thereby adhered to the LED chip 140. Asthe first lens 150 is added with 0.01 to 0.5 weight percent titaniumdioxide particles, the light refractive index of the first lens 150 isincreased to about 1.61. Therefore, the light extraction efficiency ofLED device 100 according to some embodiments of the present disclosurecan be enhanced comparing to the prior art LED devices.

Please refer to FIG. 4A again, which illustrates the second lens 160disposed on or outside the first lens 150. In some embodiments of thepresent disclosure, the second lens 160 directly contacts the first lens150, and the second lens 160 is made of silicone epoxy resin havingtitanium dioxide particles dispersed within, wherein the titaniumdioxide particles are at a content in a range of about 0.5 to about 0.2weight percent. The particle diameter of the titanium dioxide particlesis smaller than 1/10 of the wavelength of the light emitted from theblue LED chip 140, for example, smaller than 40 nm.

In some embodiments of the present disclosure, the silicone epoxy resinlayer having titanium dioxide particles dispersed therein forms thesecond lens 160 on the first lens 150 by a molding process. In otherwords, the forming process of the second lens 160 is similar to theforming process of the first lens 150. The difference between theforming processes is that a higher content of titanium dioxide particlesis mixed within the silicone epoxy resin layer of the second lens 160.

In other embodiments of the present disclosure, the silicone epoxy resinlayer is formed on the first lens 150 by a molding process. After that,a thin titanium dioxide film is deposited on the silicone epoxy resinlayer by a vacuum deposition process, such that the structure of thethin titanium dioxide film overlaying the silicone epoxy resin layerforms the second lens 160.

In other embodiments of the present disclosure, the second lens 160 isconfigured to alter the light pattern of the emitted light. The contentof the titanium dioxide particles in the silicone epoxy resin layer isin the range of about 0.5 to about 2 weight percent, which makes therefractive index of the second lens 160 is smaller than that of thefirst lens 150, so the light transmittance in silicone epoxy resin layerof the second lens 160 is decreased, and the effect of altering thelight pattern can be achieved.

According to the test results shown in FIGS. 2 and 3, when the contentof titanium dioxide particles in the silicone epoxy resin layer ishigher than a critical proportion, the titanium dioxide particlesaggregate and form large particles. Such large particles may haveparticle sizes larger than 1/10 of blue light wavelength, therebyresulting in Rayleigh scattering in the silicone epoxy resin layer andcausing the transmittance of the blue light to be decreased. The secondlens 160 is specifically designed to take advantage of Rayleighscattering caused by the large titanium dioxide particles, such that thelight scattering effect in the second lens 160 is increased and thetransmittance of the light toward directly above from the second lens160 is reduced. Furthermore, the light in the second lens 160 will bereflected more frequently, and part of the light will be refractedagain, so the light distribution pattern of the light emitted from thelenses will be altered as the target of the design.

FIGS. 4B and 4C respectively show the sample of traced rays and theCandela plot for light distribution of the LED device 100 illustrated inFIG. 4A. The transmittance of the light emitted from the upper side ofthe LED device 100 is reduced, and a part of the reflected light isrefracted again by the lenses. Therefore, the light distribution patternof the LED device 100 has a bat-wing shape, as shown in FIG. 4C.Accordingly, the LED device 100 is able to provide shorter light mixingdistance, and thus the thinner backlight module design can be achievedwith the LED device 100.

Conversely, the conventional LED devices, such as the LED device 10shown in FIG. 1A, are required to have secondary optical lenses coveringthe LED package to achieve the light distribution pattern similar as theone shown in FIG. 4C.

In some embodiments of the present disclosure, the concentration of thetitanium dioxide particles dispersed in the second lens 160 can beadjusted in order to provide the desired light pattern. For example,when the light emitted toward directly above the LED device is requiredto have higher intensity, the content of titanium dioxide particlesadded during the process of forming the second lens 160 should be less.Alternatively, when light emitted toward directly above the LED deviceis required to have lower intensity, the content of titanium dioxideparticles added during the process of forming the second lens 160 shouldbe more.

In some embodiments of the present disclosure, the first lens 150 andthe second lens 160 are two planar layers or layers having planarsurfaces. In some other embodiments of the present disclosure, the firstlens 150 and the second lens 160 may be two layers with arc shapes, forexample, lenses with convex-shaped or concave-shaped structures.

In some embodiments of the present disclosure, the LED structure 120 isformed on the substrate 110, such that the LED chip 140 is electricallyconnected to the substrate through the first pad 132 and the second pad134 and adhered to the substrate 110 by an adhesive. After the LEDstructure 120 is formed, the first lens 150 is formed over or on the LEDchip 140, and the second lens 160 is formed over or on the first lens150.

In some other embodiments of the present disclosure, the first lens 150is formed on the LED chip 140, and then the second lens 160 is formed onthe first lens 150. After the lenses are formed, the LED structure 120having the lenses is electrically connected to the substrate 110 throughthe first pad 132 and the second pad 134, and the LED chip 140 isadhered to the substrate 110 by an adhesive.

FIG. 5A illustrates an LED device 200 according to some embodiments ofthe present disclosure. In the LED device 200, an LED package structure220 is a full-encapsulation package. The first lens 250 and the secondlens 260 encapsulate the top surface 242 and the side surfaces 244 ofthe LED chip 240. The LED chip 240 is disposed on the substrate 210 andelectrically connected to the circuits of the substrate 210 through thefirst pad 232 and the second pad 234.

In some embodiments of the present disclosure, the LED chip 240 has afirst dimension D1 as the width, the second lens has a second dimensionD2 as the width, and the second dimension D2 is smaller or equal to 1.2times of the first dimension D1. Therefore, the LED package structure220 is a chip-scale package LED structure.

FIG. 5B illustrates an LED device 300 according to some otherembodiments of the present disclosure. In LED device 300, the LEDpackage structure 320 is a full-encapsulation package with a polygonalshape. The first lens 350 and the second lens 360 encapsulate the topsurface and the side surfaces of the LED chip 340. The LED chip 340 isdisposed on the substrate 310 and is electrically connected to thecircuits of the substrate through the first pad 332 and the second pad334.

The part of the first lens 350 encapsulating the top surface of the LEDchip 340 has the first thickness T1, and the part of the first lens 350encapsulating the side surface of the LED chip 340 has the secondthickness T2. In some embodiments of the present disclosure, the firstthickness T1 may not equal to the second thickness T2. The firstthickness T1 and the second thickness T2 of the first lens 350 may beadjusted respectively based on the design requirements, such that thedesired or different light extraction efficiencies at the top and sidesurfaces of the LED package structure 320 can be achieved.

The part of the second lens 360 encapsulating the top surface of the LEDchip 340 has the third thickness T3, and the part of the second lens 360encapsulating the side surface of the LED chip 340 has the fourththickness T4. In some embodiments of the present disclosure, the thirdthickness T3 may not equal to the fourth thickness T4. In theembodiments that the second lens 360 is formed by a process ofdepositing a titanium dioxide film on the silicone epoxy resin layer,the thickness at different parts of the silicone epoxy resin layer canbe adjusted during the process of forming the second lens 360, such thatthe different parts of the second lens 360 can have the requiredcontents of titanium dioxide particles respectively. The third thicknessT3 and the fourth thickness T4 may be adjusted respectively based on thedesign requirements, such that the ideal light distribution patterns atthe top and side surfaces of the LED package structure 320 can beachieved.

FIG. 6A illustrates an LED package structure 420 according to someembodiments of the present disclosure. The main difference between theLED package structure 420 and the LED package structures 220 and 320 isthat the LED package structure has a frame 422, wherein the frame 422may be made of a ceramic material or an epoxy resin material.

In the LED package structure 420, the first pad 432 is electricallyconnected to the first extended pad 426 through a guide hole 424 in theframe 422. The second pad 434 is electrically connected to the secondextended pad 428 through another guide hole 424 in the frame 422. Thefirst lens 450 is located over the frame 422 and encapsulates the LEDchip 440. The second lens 460 is located over the frame 422 andencapsulates the first lens 450.

FIG. 6B illustrates an LED package structure 520 according to someembodiments of the present disclosure. The LED package structure 520 isa single-sided illumination package structure. A protective layer 570 islocated at the side 544 of the LED chip 540, where the protective layer570 is made of an opaque material. The first lens 550 is located on theprotective layer 570 and encapsulates the top surface 542 of the LEDchip 540. The second lens 560 encapsulates the first lens 550.

According to the LED device disclosed in the embodiments of the presentdisclosure, a two-layer micro-lenses structure, i.e., the first lens andthe second lens, is disposed to encapsulate the LED chip. In someembodiments of the present disclosure, such structure can be applied to,for example, the encapsulation package of a mini LED package structureor a micro LED package structure, such as a chip-scale package or awafer-scale package.

The LED devices disclosed in the embodiments of the present disclosurecan be applied to, for example, display devices or lighting devices, butnot limited to these. More specifically, the LED devices can be utilizedin various lighting devices or components, at least including thebacklight modules of the display devices, such as the direct-typebacklight modules or the edge-lit backlight modules, the flash lamps,the projection instruments, the glare lighting fixtures, such as the carlights, the searchlights, the flashlights, the work lights, the outdoorhigh bay lights, and the landscape lights, the low-angle lights, andetc.

Given the backlight sources in a display device as an illustrativeembodiment, the improvements provided by the present disclosure areexpounded in Table 1 below, which compares the backlight moduleutilizing the LED device of the present disclosure to the one utilizingthe conventional LED devices.

TABLE 1 Light Extraction Effect on LEE Efficiency (LEE) of LED MadeBacklight Source Optics of Lenses at the Lens by the Lenses ConventionalSecondary optical lens 90% (lens material: No positive LED Devicescovering the LED Polymethylmethacrylate) effect package is required 85%(lens material: Polycarbonate) The LED Devices The lenses encapsulate115% Improving 15% of the Present the LED chip directly. Disclosure Asecondary optical lens is not required, so the volume is reduced.

FIG. 7 illustrates an exploded view of a backlight module 700 for adisplay device. The backlight module 700 includes a backplate 710, aplurality light strips 720, a backlight cavity 730, and a plurality ofoptical films 740.

A plurality of light strips 720 are disposed on the backplate 710, andeach of the light strips 720 includes a circuit board 722 and LEDcomponents 724. The LED components 724 have the first lens and thesecond lens as described above.

The backlight cavity 730 is set over the backplate 710 and the lightstrips 720. The bottom surface of the reflector, as the bottom of thebacklight 730, has a plurality of openings 732 respectivelycorresponding to the plurality of LED components 724. In someembodiments of the present disclosure, the backlight module 700 can beapplied in slim display devices or thin display devices, which requirethe height of the backlight cavity 730 to be less than 10 mm.

A plurality of optical films 740 are disposed over the backlight cavity730. The optical films may be, for example, a diffuser plate, a prismplate, a diffuser sheet, or the like, which can adjust the opticalcharacteristics of the backlight module 700 as the requirements.

In some embodiments of the present disclosure, a thin display device isdisclosed, which requires the height of the optical cavity within thedisplay device is less than 10 mm. The backlight module of the displaydevice includes the LED devices or the LED package structures of theembodiments illustrated in FIG. 4A, 5A, 5B, 6A, or 6B. Therefore, thesecondary optical lens required in the conventional LED devices can beomitted. In addition, the light extraction efficiency and thelight-mixing effect of the thin display devices and the lighting deviceshaving small optical cavity heights can be enhanced by utilizing the LEDpackages of the present disclosure.

The foregoing has outlined features of several embodiments so that thoseskilled in the art can better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A light-emitting diode (LED) device, comprising:an LED chip; and a package structure directly contacting the LED chip,wherein the package structure comprises: a first lens disposed over theLED chip, wherein the first lens directly contacts the LED chip, thefirst lens is configured to increase light extraction efficiency of theLED device, and the first lens comprises a first content of titaniumdioxide; and a second lens disposed over the first lens, wherein thesecond lens is configured to alter a light pattern of the LED device,the second lens comprises a second content of titanium dioxide, and thesecond content of titanium dioxide is more than the first content oftitanium dioxide.
 2. The LED device of claim 1, wherein a material ofthe first lens and the second lens comprises silicone epoxy resin. 3.The LED device of claim 1, wherein the first content of titanium dioxideof the first lens is in a range from 0.01 to 0.5 weight percent of thefirst lens.
 4. The LED device of claim 1, wherein the second content oftitanium dioxide of the second lens is in a range from 0.5 to 2 weightpercent of the second lens.
 5. The LED device of claim 1, wherein anaverage particle diameter of the titanium dioxide of the first lens andthe titanium dioxide of the second lens is smaller than 1/10 of awavelength of light emitted from the LED device.
 6. The LED device ofclaim 1, wherein the first content of titanium dioxide of the first lensis less than 0.5 weight percent of the first lens, and the secondcontent of titanium dioxide of the second lens is more than 0.5 weightpercent of the second lens.
 7. The LED device of claim 1, wherein alight refractive index of the second lens is smaller than a lightrefractive index of the first lens.
 8. The LED device of claim 1,wherein a light transmittance of the second lens is smaller than a lighttransmittance of the first lens.
 9. The LED device of claim 1, whereinan average particle diameter of the titanium dioxide of the first lensand the titanium dioxide of the second lens is smaller than 40 nm. 10.The LED device of claim 1, wherein the titanium dioxide of the firstlens is dispersed in the first lens.
 11. The LED device of claim 1,wherein the titanium dioxide of the second lens is dispersed in thesecond lens.
 12. The LED device of claim 1, wherein the second lensincludes a resin material, and the titanium dioxide of the second lensis formed as a thin film overlaying the resin material of the secondlens.
 13. The LED device of claim 1, wherein the LED device is achip-scale package structure.
 14. The LED device of claim 1, wherein theLED device is a mini LED device or a micro LED device.
 15. A displaydevice comprising a backlight module, wherein the backlight modulecomprising: an LED device comprising: an LED chip; and a packagestructure directly contacting the LED chip, wherein the packagestructure comprises: a first lens disposed over the LED chip, whereinthe first lens directly contacts the LED chip, the first lens isconfigured to increase light extraction efficiency of the LED device,and the first lens comprises a first content of titanium dioxide; and asecond lens disposed over the first lens, wherein the second lens isconfigured to alter a light pattern of the LED device, the second lenscomprises a second content of titanium dioxide, and the second contentof titanium dioxide is more than the first content of titanium dioxide;and an optical cavity disposed over the the LED chip.
 16. The displaydevice of claim 15, wherein the optical cavity having a height smallerthan 10 mm.
 17. The display device of claim 16, wherein the backlightmodule is a direct-type backlight module.
 18. A lighting devicecomprising an LED device, wherein the LED device comprising: an LEDchip; and a package structure directly contacting the LED chip, whereinthe package structure comprises: a first lens disposed over the LEDchip, wherein the first lens directly contacts LED chip, the first lensis configured to increase light extraction efficiency of the LED device,and the first lens comprises a first content of titanium dioxide; and asecond lens disposed over the first lens, wherein the second lens isconfigured to alter a light pattern of the LED device, the second lenscomprises a second content of titanium dioxide, and the second contentof titanium dioxide is more than the first content of titanium dioxide.19. The lighting device of claim 18, wherein the LED device comprises amini LED or a micro LED.
 20. The lighting device of claim 18, whereinthe LED device has a light distribution pattern with a bat-wing shape.